Significance

Isotopic evidence showing that Rome’s lead water pipes were the primary source of lead pollution in the city’s runoff reveals the sedimentary profile of lead pollution in the harbor at Ostia to be a sensitive record of the growth of Rome’s water distribution system and hence, of the city itself. The introduction of this lead pipe network can now be dated to around the second century BC, testifying to a delay of about a century and a half between the introduction of Rome’s aqueduct system and the installation of a piped grid. The diachronic evolution of anthropogenic lead contamination is able to capture the main stages of ancient Rome's urbanization until its peak during the early high empire.

Abstract

Heavy metals from urban runoff preserved in sedimentary deposits record long-term economic and industrial development via the expansion and contraction of a city’s infrastructure. Lead concentrations and isotopic compositions measured in the sediments of the harbor of Ostia—Rome’s first harbor—show that lead pipes used in the water supply networks of Rome and Ostia were the only source of radiogenic Pb, which, in geologically young central Italy, is the hallmark of urban pollution. High-resolution geochemical, isotopic, and 14C analyses of a sedimentary core from Ostia harbor have allowed us to date the commissioning of Rome’s lead pipe water distribution system to around the second century BC, considerably later than Rome’s first aqueduct built in the late fourth century BC. Even more significantly, the isotopic record of Pb pollution proves to be an unparalleled proxy for tracking the urban development of ancient Rome over more than a millennium, providing a semiquantitative record of the water system’s initial expansion, its later neglect, probably during the civil wars of the first century BC, and its peaking in extent during the relative stability of the early high Imperial period. This core record fills the gap in the system’s history before the appearance of more detailed literary and inscriptional evidence from the late first century BC onward. It also preserves evidence of the changes in the dynamics of the Tiber River that accompanied the construction of Rome’s artificial port, Portus, during the first and second centuries AD.

Physical and social well-being in old age are linked to self-assessments of life worth, and a spectrum of behavioral, economic, health, and social variables may influence whether aging individuals believe they are leading meaningful lives.